Oscillator, electronic device, and moving object

ABSTRACT

An oscillator includes a substrate, a detection flap plate which is disposed facing the substrate, and an elastically deformable beam portion which displaceably supports the detection flap plate in a Z axis direction with respect to the substrate, in which the detection flap plate is displaced to the substrate side in a range in which recovery force of the beam portion is larger than the electrostatic force which is formed between the substrate and the detection flap plate. That is, when a boundary at which electrostatic force and recovery force are equal is a pull in critical point, the detection flap plate is displaced within a region above the pull in critical point.

BACKGROUND

1. Technical Field

The present invention relates to an oscillator, an electronic device,and a moving object.

2. Related Art

In the related art, a configuration described in JP-T-2008-514968 isknown as a gyro sensor (angular velocity sensor). The gyro sensordescribed in JP-T-2008-514968 is configured to have a frame shape massportion (frame), a movable portion (vibration device) which is disposedinside the mass portion, a beam portion (suspension piece) whichconnects the movable portion and the frame, and an electrode which isdisposed facing the movable portion, and to vibrate in a Z axisdirection while the movable portion torsionally deforms the beam portionby Coriolis force when angular velocity is applied about an X axis in astate in which the mass portion is vibrated in a Y axis direction. Dueto vibration of such a movable portion, since electrostatic capacitorwhich is formed between the movable portion and the electrode ischanged, it is possible to detect angular velocity that is applied tothe gyro sensor based on the change in electrostatic capacitor.

However, in the configuration of JP-T-2008-514968, there is a concernthat when the movable portion is greatly displaced to an electrode side,electrostatic force (electrical attractive force) which is generatedbetween the movable portion and the electrode is larger than recoveryforce (force which returns to a natural state) of the beam portion, andthe movable portion sticks to the electrode due to the electrostaticforce.

SUMMARY

An advantage of some aspects of the invention is to provide anoscillator, an electronic device, and a moving object that are able toreduce sticking of the movable portion to the substrate.

Such an advantage is achieved by the aspects of the invention below.

According to an aspect of the invention, there is provided an oscillatorincluding a substrate, a movable portion which is disposed facing thesubstrate, and an elastically deformable beam portion which displaceablysupports the movable portion in a thickness direction of the substratewith respect to the substrate, in which the movable portion is displacedto the substrate side in a range in which recovery force of the beamportion is larger than electrostatic force which is formed between thesubstrate and the movable portion.

Thereby, an oscillator is obtained which is able to reduce sticking ofthe movable portion to the substrate.

In the oscillator according to the aspect of the invention, in a sideview of the substrate, when a position at which the electrostatic forceand recovery force are equal is a movable critical point, it ispreferable that the movable portion contacts the substrate prior toexceeding the movable critical point.

Thereby, it is possible to reduce sticking of the movable portion to thesubstrate.

In the oscillator according to the aspect of the invention, it ispreferable that the movable critical point is positioned further on theopposite side from the movable portion than a surface of the substratefacing the movable portion.

Thereby, it is possible to reduce sticking of the movable portion to thesubstrate.

In the oscillator according to the aspect of the invention, it ispreferable that the substrate has an electrode which is disposed facingthe movable portion and a base substrate which supports the electrode.

Thereby, for example, it is possible detect an amount of displacement ofthe movable portion by detecting a change in electrostatic capacitorwhich is formed between the movable portion and the electrode. For thisreason, for example, it is possible to favorably utilize a physicalquantity sensor which detects a physical quantity such as accelerationor angular velocity.

In the oscillator according to the aspect of the invention, it ispreferable that the movable portion rotates about the rotary shaft alongthe in-plane direction of the substrate.

Thereby, it is possible to smoothly displace the movable portion.

In the oscillator according to the aspect of the invention, it ispreferable that the movable portion has a protruding portion whichprotrudes from a tip end portion to a tip end side.

Thereby, it is assumed that it is possible to reduce a contact area withthe substrate when the movable portion contacts the substrate. For thisreason, it is possible to more effectively reduce sticking of themovable portion to the substrate.

In the oscillator according to the aspect of the invention, it ispreferable that the substrate has a step portion which is provided at aposition facing the tip end portion of the movable portion and isconcave to the opposite side from the movable portion.

Thereby, it is possible to reduce contact between the movable portionand the substrate.

In the oscillator according to the aspect of the invention, it ispreferable that concavities and convexities are formed at a location atwhich it is possible for the substrate to contact the movable portion.

Thereby, it is assumed that it is possible to reduce a contact area withthe substrate when the movable portion contacts the substrate. For thisreason, it is possible to more effectively reduce sticking of themovable portion to the substrate.

According to another aspect of the invention, there is provided anelectronic device including the oscillator of the aspect of theinvention.

Thereby, an electronic device with high reliability is obtained.

According to still another aspect of the invention, there is provided amoving object including the oscillator of the aspect of the invention.

Thereby, a moving object with high reliability is obtained.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be described with reference to the accompanyingdrawings, wherein like numbers reference like elements.

FIG. 1 is a planar view illustrating an oscillator according to a firstembodiment of the invention.

FIG. 2 is a sectional view taken along line II-II in FIG. 1.

FIG. 3 is a sectional view for describing problems of the related art.

FIG. 4 is a sectional view for describing problems of the related art.

FIG. 5 is a sectional view of the oscillator illustrated in FIG. 1.

FIG. 6 is a sectional view of the oscillator illustrated in FIG. 1.

FIG. 7 is a sectional view illustrating a modification example of afixed detection electrode.

FIG. 8 is a planar view illustrating a modification example of afunctional element.

FIG. 9 is a sectional view along line IX-IX in FIG. 8.

FIG. 10 is a planar view illustrating a detection flap plate which isprovided in an oscillator according to a second embodiment of theinvention.

FIG. 11 is a planar view illustrating a modification example of thefixed detection electrode.

FIG. 12 is a planar view illustrating a modification example of thedetection flap plate.

FIG. 13 is a planar view illustrating a modification example of thedetection flap plate.

FIG. 14 is a sectional view illustrating an oscillator according to athird embodiment of the invention.

FIG. 15 is a sectional view illustrating a state in which the detectionflap plate contacts the substrate.

FIG. 16 is a planar view illustrating a corner portion that is providedon the substrate.

FIG. 17 is a sectional view along line XVII-XVII in FIG. 16.

FIG. 18 is a planar view illustrating a modification example of thecorner portion which is illustrated in FIG. 16.

FIG. 19 is a planar view illustrating a modification example of thecorner portion which is illustrated in FIG. 16.

FIG. 20 is a perspective view illustrating a configuration of amobile-type (or a notebook-type) personal computer to which anelectronic device of the aspect of the invention is applied.

FIG. 21 is a perspective view illustrating a configuration of a mobilephone (also including PHS) to which the electronic device of the aspectof the invention is applied.

FIG. 22 is a perspective view illustrating a configuration of a digitalstill camera to which the electronic device of the aspect of theinvention is applied.

FIG. 23 is a perspective view illustrating an automobile to which amoving object of the aspect of the invention is applied.

DESCRIPTION OF EXEMPLARY EMBODIMENTS

An oscillator, an electronic device, and a moving object of theinvention will be described below in detail based on the embodimentswhich are illustrated in the drawings.

First Embodiment

First, an oscillator according to the first embodiment of the inventionwill be described.

FIG. 1 is a planar view illustrating an oscillator according to a firstembodiment of the invention. FIG. 2 is a sectional diagram taken alongline II-II in FIG. 1. FIGS. 3 and 4 are each sectional views fordescribing problems of the related art. FIGS. 5 and 6 are each sectionalviews of the oscillator illustrated in FIG. 1. FIG. 7 is a sectionalview illustrating a modification example of a fixed detection electrode.FIG. 8 is a planar view illustrating a modification example of afunctional element. FIG. 9 is a sectional view along line IX-IX in FIG.8. Note that, in the description below, an X axis, a Y axis, and a Zaxis are set as three axes which are orthogonal to each other. Inaddition, a direction along the X axis is referred to as an “X axisdirection”, a direction along the Y axis is referred to as a “Y axisdirection”, and a direction along the Z axis is referred to as a “Z axisdirection”.

An oscillator 1 shown in FIGS. 1 and 2 is a gyro sensor (angularvelocity sensor) which is able to detect an angular velocity ωy aboutthe Y axis. Such an oscillator 1 has a substrate 2, a lid 3, and afunctional element 4. Note that, for convenience of description, in FIG.1, illustration of the substrate 2 and the lid 3 is omitted.

The substrate 2 has a base substrate 21 and a fixed detection electrode22 which is supported on the base substrate 21. The base substrate 21has a concave portion 211 which opens to an upper surface and a post(projecting portion) 212 which is provided within the concave portion211, and the functional element 4 is supported by the upper surface andthe post 212. In addition, the fixed detection electrode 22 is providedwith two bottom surfaces 211 a of the concave portion 211. Meanwhile,the lid 3 has a concave portion 31 which is open on a lower surface. Thebase substrate 21 and the lid 3 are bonded so as to form an internalspace S with the concave portion 211 and the concave portion 31. Then,the functional element 4 is accommodated in the internal space S. Notethat, it is preferable for the internal space S to be in a reducedpressure state. Thereby, it is possible to reduce viscosity resistanceand effectively vibrate the functional element 4.

In the embodiment, the base substrate 21 is formed from a glasssubstrate and the lid 3 is formed from a silicon substrate. For thisreason, it is possible to bond the base substrate 21 and the lid 3 byanodic bonding. However, the base substrate 21 and the lid 3 are notlimited to such materials, and the bonding method of the base substrate21 and the lid 3 is not limited to such a method.

As described above, the functional element 4 is disposed in the internalspace S, and the upper surface of the base substrate 21 and the post 212are bonded. Such a functional element 4 has two structures 40 (40 a and40 b). The two structures 40 a and 40 b are provided lined up in the Xaxis direction, and are symmetrical along the Y axis with respect to avirtual straight line α.

The structure 40 has a mass portion (vibration portion) 41, a drivingpanel portion 42, a fixing portion 43, a movable driving electrode 44,fixed driving electrodes 45 and 46, a detection flap plate (movableportion) 47, and a beam portion 48. Such a structure 40 is integrallyformed by patterning by etching and the like a silicon substrate withconductivity that is doped with impurities such as phosphorus and boron.

The mass portion 41 is a rectangular frame and is disposed on the centerportion of the structure 40. Then, one end portion of the driving panelportion 42 is connected to each of four corners of the mass portion 41.In addition, another end portion of the driving panel portion 42 isconnected to the fixing portion 43, and the fixing portion is bonded(fixed) to the upper surface of the base substrate 21 or the post 212.Thereby, there is a state in which the mass portion 41 and a drivingpanel portion 42 are supported in a state of floating away from thesubstrate 2. Then, it is possible to vibrate the mass portion 41 in theX axis direction with respect to the fixing portion 43 by expanding andcontracting (elastically deforming) the driving panel portion 42 in theX axis direction. The joining method of the fixing portion 43 and thepost 212 is not particularly limited, but, for example, it is possibleto use anodic bonding.

The movable driving electrodes 44 are provided on the mass portion 41,and in the embodiment, a total of four movable driving electrodes 44 areprovided in the mass portion 41, two at the +Y axis side and two at the−Y axis side. The movable driving electrodes 44 are tooth shapedprovided with a stem portion which extends from the mass portion 41 inthe Y axis direction and a plurality of branch portions which extendfrom the stem portion in the X axis direction. Meanwhile, the fixeddriving electrodes 45 and 46 are bonded (fixed) to the base substrate21. The fixed driving electrodes 45 and 46 are provided facing themovable driving electrode 44, and the movable driving electrode 44 isdisposed between the fixed driving electrodes 45 and 46. In addition,the fixed driving electrodes 45 and 46 are tooth shaped provided withthe stem portion which extends in the Y axis direction and the branchportion which extends from the stem portion in the X axis direction.

For this reason, when the driving voltage is applied between the movabledriving electrode 44 and the fixed driving electrodes 45 and 46, anelectrostatic force is generated between the movable driving electrode44 and the fixed driving electrodes 45 and 46, thereby, it is possibleto expand and contract the driving panel portion 42 in the X axisdirection and the mass portion 41 is vibrated (driven) in the X axisdirection. Note that, in the structure 40 a and the structure 40 b, thedisposition of the fixed driving electrode 45 and the fixed drivingelectrode 46 are opposite. That is, in the structure 40 a, the fixeddriving electrode 45 is positioned on the −X axis side of the movabledriving electrode 44, with respect to the fixed driving electrode 46which is positioned on the +X axis side, in the structure 40 b, thefixed driving electrode 45 is positioned on the +X axis side of themovable driving electrode 44, and the fixed driving electrode 46 ispositioned on the −X axis side. For this reason, the mass portion 41 ofthe structure 40 a and the mass portion 41 of the structure 40 b arevibrated in a reverse phase in the X axis direction so as to come closeto and be separated from each other. Thereby, it is possible to cancelvibration of two mass portions 41, and it is possible to reducevibration leakage.

Note that, in the embodiment, as described above, an aspect(electrostatic drive system) which vibrates the mass portion 41 due toelectrostatic force is described, but the system which vibrates the massportion 41 is not particularly limited, and it is also possible to applya piezoelectric drive system, an electromagnetic drive system whichutilizes a Lorentz force of a magnetic field, and the like.

The detection flap plate 47 is disposed inside the mass portion 41. Inaddition, the detection flap plate 47 has a rectangular plate shape, andis supported on the mass portion 41 via the beam portion 48 on one endportion in the Y axis direction. In such a detection flap plate 47, thebeam portion 48 is caused to torsionally deform (elastically deform) andis rotated (displaced) about a rotary shaft J that is formed by the beamportion 48 due to Coriolis force by angular velocity ωy being appliedabout the Y axis in the oscillator 1 of a state in which the massportion 41 is vibrated in the X axis direction. Thereby, it is possibleto smoothly displace the detection flap plate 47 in the Z axisdirection.

The fixed detection electrode 22 is provided in a region which faces thedetection flap plate 47 of the base substrate 21 (region that overlapsin planar view viewed from the Z axis direction), and electrostaticcapacitor C is formed between the fixed detection electrode 22 and thedetection flap plate 47. As described above, when the detection flapplate 47 is displaced (inclined) about the rotary shaft J by the angularvelocity ωy, since the size of the electrostatic capacitor C is changed,it is possible to detect the angular velocity ωy based on the change ofthe electrostatic capacitor C. Note that, the configuration material ofthe fixed detection electrodes 22 is not particularly limited as long asthe material has conductivity, and for example, it is possible to usealuminum, gold, platinum, or indium tin oxide (ITO).

The shape of the oscillator 1 is described above. Next, the operation ofthe oscillator 1 will be described. Driving voltage is applied betweenthe movable driving electrode 44 and the fixed driving electrodes 45 and46, and the mass portion 41 of the structure 40 a and the mass portion41 of the structure 40 b are vibrated at a reverse phase in the X axisdirection at a predetermined frequency. In this state, when the angularvelocity ωy is applied about the Y axis in the oscillator 1, Coriolisforce operates, and the detection flap plate 47 of the structure 40 aand the detection flap plate 47 of the structure 40 b are displaced inthe reverse phase (in the Z axis direction) about the rotary shaft J.Due to the detection flap plate 47 being displaced, a gap between thedetection flap plate 47 and the fixed detection electrode 22 is changed,and accompanying this, electrostatic capacitor C is changed, andtherefore it is possible to obtain the angular velocity ωy by detectingan amount of change of the electrostatic capacitor C.

Next, one feature of the oscillator 1 will be described concerning amovable range of the detection flap plate 47. As described above, thedetection flap plate 47 is set so as to vibrate in the Z axis directiondue to angular velocity ωy being applied in a state in which the massportion 41 is driven. In the oscillator 1, when the detection flap plate47 vibrates in the Z axis direction, there is a configuration in whichsticking to the fixed detection electrode 22 is reduced by electrostaticforce (electrical attractive force) which acts within the fixeddetection electrode 22.

First, sticking to the fixed detection electrode 22 of the detectionflap plate 47 due to electrostatic force will be described. First, asshown in FIG. 3, in a side surface view of the oscillator 1 (horizontalplane view viewed from the X axis direction), a boundary in whichelectrostatic force which acts within the fixed detection electrode 22and recovery force of the beam portion 48 (force which is to return to anatural state and a spring constant) are equal is set to a pull incritical point (movable critical point) L. That is, if the detectionflap plate 47 is positioned further on the upper side (+Z axis side)than the pull in critical point L, recovery force of the beam portion 48is larger than electrostatic force which acts between the detection flapplate 47 and the fixed detection electrode 22, and if at least a part ofthe detection flap plate 47 is positioned further on the lower side (−Zaxis side) than the pull in critical point L, recovery force of the beamportion 48 is smaller than electrostatic force which acts between thedetection flap plate 47 and the fixed detection electrode 22.

For this reason, when for example, excessive angular velocity ωy orother external force in which the detection flap plate 47 is displacedin the Z axis direction is applied and the detection flap plate 47 isdisplaced further up to the lower side than the pull in critical pointL, there is a concern that recovery force of the beam portion 48 doesnot counter electrostatic force, the detection flap plate 47 isattracted to the fixed detection electrode 22, and as shown in FIG. 4,sticks to the substrate 2.

Therefore, as shown in FIG. 5, in the oscillator 1, a spring constant ofthe beam portion 48, area of the fixed detection electrode 22, and thelike are designed such that the pull in critical point L is positionedfurther on the lower side (opposite side from the detection flap plate47) than a surface which faces the detection flap plate 47 of thesubstrate 2 (upper surface of the fixed detection electrode 22 in theembodiment). When designing in this manner, as shown in FIG. 6, prior tothe detection flap plate 47 exceeding the pull in critical point L, thedetection flap plate 47 collides with the substrate 2 and furtherdisplacement is regulated. In other words, even if the detection flapplate 47 is displaced in the −Z axis direction until contacting thesubstrate 2, the detection flap plate 47 is not displaced further to thelower side than the pull in critical point L. That is, the detectionflap plate 47 contacts the substrate 2 prior to exceeding the pull incritical point L. For this reason, ordinarily, it is possible to vibratethe detection flap plate 47 within a region further on the upper sidethan the pull in critical point L. Accordingly, as described above,according to the oscillator 1, it is possible to reduce sticking to thesubstrate 2 of the detection flap plate 47.

Note that, in the manner of the oscillator 1, since the pull in criticalpoint L is positioned further on the lower side than the upper surfaceof the fixed detection electrode 22, for example, it is possible to setthe spring constant of the beam portion 48 in the following manner. Thatis, when the spring constant of the beam portion 48 is set as kr, adielectric constant of the internal space S is set as ε, an area of thefixed detection electrode 22 is set as Se, a voltage which is appliedbetween the detection flap plate 47 and the fixed detection electrode 22is set as V, a separation distance between the detection flap plate 47and the fixed detection electrode 22 in an initial state is set as d,and a length of the detection flap plate 47 (length in the Y axisdirection) is set as l, it is possible to position the pull in criticalpoint L further to the lower side than the upper surface of the fixeddetection electrode 22 by satisfying formula (1) below.Kr>ε·Se·V2·(1/d(3/2))/√2  (1)

The oscillator 1 of the embodiment is described above. Note that, in theoscillator 1 of the embodiment, when the detection flap plate 47 isexcessively displaced in the Z axis direction, there is a concern that ashort is generated during contact since there is contact with the fixeddetection electrode 22. For this reason, as shown in FIG. 7, when thedetection flap plate 47 is excessively displaced in the Z axisdirection, there may be a configuration so as to contact a bottomsurface 211 a of the concave portion 211 and not the fixed detectionelectrode 22. The bottom surface 211 a may not necessarily be exposed bythe substrate 2. For example, a conductive film on an upper surface ofthe substrate 2 or a conductive film which is electrically connected tothe detection flap plate 47 may be provided. In this case, there may bethe bottom surface 211 a or the pull in critical point L that ispositioned further on the lower side than the conductive film.

Note that, opposing areas of the detection flap plate 47 and the fixeddetection electrode 22 are decreased by setting the configurationillustrated in FIG. 7. In addition, since the fixed detection electrode22 is disposed near to the beam portion 48 side, when the detection flapplate 47 is displaced, an amount of change of the gap between thedetection flap plate 47 and the fixed detection electrode 22 is reduced.For this reason, it is possible to reduce variation of electrostaticforce between the detection flap plate 47 and the fixed detectionelectrode 22 and more effectively reduce sticking to the substrate 2 ofthe detection flap plate 47.

The oscillator 1 of the embodiment 1 is described above. Note that, inthe embodiment, a configuration in which each structure 40 is providedwith one detection flap plate 47 is described, but the number ofdetection flap plates 47 is not limited to one. For example, as shown inFIGS. 8 and 9, two detection flap plates 47 may be provided lined up inthe Y axis direction. In this configuration, two detection flap plates47 are disposed such that free ends are turned away from each other, butfor example, may be disposed such that the free ends face each other,and may be disposed such that the free ends face in the same directionas each other.

Second Embodiment

Next, an oscillator according to the second embodiment of the inventionwill be described.

FIG. 10 is a planar view illustrating a detection flap plate which isprovided with an oscillator according to a second embodiment of theinvention. FIG. 11 is a planar view illustrating a modification exampleof the fixed detection electrode. FIGS. 12 and 13 are each planar viewsillustrating a modification example of the detection flap plate.

The oscillator according to the embodiment is mainly the same as theoscillator according to the first embodiment described above aside fromthe configuration of the functional element (shape of the detection flapplate) which is different.

Note that, the description below relates to the oscillator of the secondembodiment, the description focuses on the differences from theembodiment described above, and similar matter is omitted from thedescription. In addition, the configurations in FIGS. 10 to 12 which arethe same as the embodiments described above are given the same referencenumerals.

In the functional element 4 illustrated in FIG. 10, the detection flapplate 47 has a protruding portion 471 which protrudes from the tip endportion to the tip end side. In the embodiment, a plurality ofapproximately rectangular protruding portions 471 are provided separatedfrom each other. By providing such a protruding portion 471, since theconcavities and convexities are formed on the tip end of the detectionflap plate 47, it is possible to reduce a contact area with thesubstrate 2 when the detection flap plate 47 contacts the substrate 2 incomparison to, for example, the first embodiment described above.Accordingly, it is possible to reduce influence of the electrostaticforce described above, and it is possible to reduce sticking to thesubstrate 2 of the detection flap plate 47 due to factors other than theelectrostatic force. Note that, as a factor other than electrostaticforce, for example, there are examples of sticking due to contactcharging due to contact between the detection flap plate 47 and thesubstrate 2, contact friction between the detection flap plate 47 andthe substrate 2 (minute concavities and convexities are involved witheach other), and the like.

It is possible for the same effects to those in the first embodimentdescribed above to also be exhibited in the second embodiment.

Note that, since contact between the protruding portion 471 and thefixed detection electrode 22 is prevented, as shown in FIG. 11, the partwhich faces the protruding portion 471 of the fixed detection electrode22 may be removed. In addition, the shape of the protruding portion 471is not particularly limited as long as it is possible to reduce thecontact area between the detection flap plate 47 and the substrate 2.For example, the protruding portion 471 may be set as a taper shape suchas a triangular shape as shown in FIG. 12, a semi-circular shape asshown in FIG. 13, and the like in which width gradually decreases towardthe tip end. In addition, the number of protruding portions 471 is notparticularly limited, and may be one.

Third Embodiment

Next, an oscillator according to the third embodiment of the inventionwill be described.

FIG. 14 is a sectional view illustrating an oscillator according to athird embodiment of the invention. FIG. 15 is a sectional viewillustrating a state in which the detection flap plate contacts thesubstrate. FIG. 16 is a planar view illustrating a corner portion thatis provided on the substrate. FIG. 17 is a sectional view along lineXVII-XVII in FIG. 16. FIGS. 18 and 19 are each planar views illustratinga modification example of the corner portion which is illustrated inFIG. 16.

The oscillator according to the embodiment is mainly the same as theoscillator according to the first embodiment described above aside fromthe configuration of the substrate being different.

Note that, the description below relates to the oscillator of the thirdembodiment, the description focuses on the differences from theembodiment described above, and similar matter is omitted from thedescription. In addition, the configurations in FIGS. 14 to 16 which arethe same as the embodiments described above are given the same referencenumerals.

In the substrate 2 illustrated in FIG. 14, a step portion (concaveportion) 213 which is concave to the lower surface is formed at aposition which faces the detection flap plate 47 of the bottom surface211 a of the concave portion 211. The step portion 213 functions as aclearance section for preventing contact between the detection flapplate 47 and the substrate 2. By providing such a step portion 213, itis possible to increase a rotation angle θ of the detection flap plate47 in comparison to a case in which there is no step portion 213 (forexample, the first embodiment described above). For this reason, alarger angular velocity ωy is able to be detected, and it is possible towiden a detection permissible range of the angular velocity ωy.

It is possible for the same effects to those in the first embodimentdescribed above to also be exhibited in the third embodiment.

Note that, in the embodiment, as shown in FIG. 15, the detection flapplate 47 is able to contact the corner portion 214 which is formed in aconnecting portion of the bottom surface 211 a and the step portion 213.For this reason, it can be said that the corner portion 214 functions asa stopper which regulates displacement of the detection flap plate 47 ormore (displacement to the −Z axis side). In this manner, since thecorner portion 214 functions as the stopper, it is preferable that thepull in critical point L is positioned below the corner portion 214 (onthe bottom surface side of the step portion 213), and more preferablypositioned below the bottom surface side of the step portion 213.Thereby, it is possible to effectively reduce sticking to the substrate2 of the detection flap plate 47.

Concavities and convexities as illustrated in FIGS. 16 and 17 may beformed in such a corner portion 214 (position which contacts thedetection flap plate 47). In the configuration in FIGS. 16 and 17, theconcavities and convexities are formed by providing a plurality ofprotrusion portions 215 of a rectangular shape which protrudes from thecorner portion 214 inside the step portion 213 separated from eachother. By configuring in this manner, in the same manner as the secondembodiment described above, since it is possible to reduce the contactarea between the substrate 2 and the detection flap plate 47 it ispossible to reduce influence of the electrostatic force, and it ispossible to reduce sticking to the substrate 2 of the detection flapplate 47 due to factors other than electrostatic force.

Note that, the shape of the protruding portion 215 is not particularlylimited as long as it is possible to reduce the contact area between thedetection flap plate 47 and the substrate 2. For example, the protrudingportion 215 may be set as a taper shape such as a triangular shape asshown in FIG. 18, a semi-circular shape as shown in FIG. 19, and thelike in which width gradually decreases toward the tip end. In addition,the number of protruding portions 215 is not particularly limited, andmay be one.

Next, an electronic device which is provided with the oscillator of theinvention will be described.

FIG. 20 is a perspective diagram illustrating a configuration of amobile-type (or a notebook-type) personal computer to which theelectronic device of the invention is applied.

In the drawing, a personal computer 1100 is configured by a main bodysection 1104 which is provided with a keyboard 1102, and a display unit1106 which is provided with a display section 1108, and the display unit1106 is supported so as to be able to rotate via a hinge structuresection with respect to the main body section 1104. The oscillator 1which functions as a gyro sensor is built in to such a personal computer1100.

FIG. 21 is a perspective view illustrating a configuration of a mobilephone (also including PHS) to which the electronic device of theinvention is applied.

In this drawing, a mobile phone 1200 includes an antenna (which is notshown in the drawings), a plurality of operation buttons 1202, areceiving port 1204, and a transmission port 1206, and a display section1208 is arranged between the operation buttons 1202 and the receivingport 1204. The oscillator 1 which functions as the gyro sensor is builtin to such a mobile phone 1200.

FIG. 22 is a perspective view illustrating a configuration of a digitalstill camera to which the electronic device of the invention is applied.

The display section 1310 is provided on the rear surface of a case(body) 1302 in the digital still camera 1300, and is configured toperform display based on the imaging signal using the CCD, and thedisplay section 1310 functions as a viewfinder which displays thesubject as an electronic image. In addition, a light-receiving unit 1304which includes an optical lens (imaging optical system), CCD, and thelike is included at the front surface side (the rear surface side in thedrawing) of the case 1302. Then, a subject image which is displayed onthe display section 1310 is confirmed by a photographer, and at thepoint in time when a shutter button 1306 is pressed, the imaging signalof the CCD is transferred and stored in a memory 1308. The oscillator 1which is used, for example, in image stabilization as the gyro sensor isbuilt in to the digital still camera 1300.

Such an electronic device is provided with the oscillator 1, andtherefore has superior reliability.

Note that, in addition to the personal computer in FIG. 20, the mobilephone in FIG. 21, and the digital still camera in FIG. 22, it is alsopossible to apply the electronic device of the invention to, forexample, a smartphone, a tablet terminal, a timepiece, an ink jet-typedischarging apparatus (for example, an ink jet printer), a laptop-typepersonal computer, a television, a video camera, a video tape recorder,a car navigation device, a pager, an electronic organizer (includingthose having a communication function), an electronic dictionary, anelectronic calculator, an electronic game device, a word processor, awork station, a video phone, a television monitor for crime prevention,a pair of electronic binoculars, a POS terminal, medical equipment (forexample, an electronic thermometer, a blood pressure meter, a bloodglucose meter, an electrocardiographic measuring device, an ultrasonicdiagnostic device, or an electronic endoscope), a fish finder, variousmeasurement equipment, an instrument (for example, an instrument for avehicle, an aircraft, or a ship), a flight simulator, and the like.

Next, a moving object of the invention will be described.

FIG. 23 is a perspective view illustrating an automobile to which themoving object of the invention is applied.

As shown in FIG. 23, the oscillator 1 is built in to an automobile 1500,and for example, it is possible to detect the posture of a vehicle 1501using the oscillator 1. The detection signal of the oscillator 1 issupplied to a vehicle body posture control device 1502, the vehicle bodyposture control device 1502 detects the posture of the vehicle 1501based on the detection signal, and according to the detection result, itis possible to control the hardness of suspension, or control brakes ofindividual wheels 1503. In addition, such posture control is able to beutilized in a biped walking robot or a radio controlled helicopter(including a drone). As above, posture control is realized in variousmobile bodies, and the oscillator 1 is incorporated.

The oscillator, the electronic device, and the moving object of theinvention are described above based on the embodiments of the drawings,but the invention is not limited thereto, and it is possible for theconfiguration of each portion to be substituted with an arbitraryconfiguration which has the same function. In addition, other arbitraryconstructions may be added to the invention.

In addition, in the embodiment described above, a configuration isdescribed in which the detection flap plate is rotated about the rotaryshaft, but as long as it is possible to displace in the Z axisdirection, the detection flap plate may displaced in any manner. Forexample, the detection flap plate may see-saw rock about the rotaryshaft, and may be displaced in the Z axis direction maintained in aposture without change. That is, the oscillator may be a see-saw rocktype, and the oscillator may be a parallel plate type.

In addition, the oscillator is not limited to a gyro sensor whichdetects angular velocity, and for example, may be a physical quantitysensor which detects a physical quantity other than angular velocity ofan acceleration sensor, an atmospheric pressure sensor, or the like. Inaddition, other than a physical quantity sensor, there may be anoscillator which is used, for example, in a generator or the like.

The entire disclosure of Japanese Patent Application No. 2015-182057,filed Sep. 15, 2015 is expressly incorporated by reference herein.

What is claimed is:
 1. An oscillator comprising: a substrate; a movablemember which is disposed facing the substrate; and an elasticallydeformable beam which supports the movable member, the movable memberbeing displaceable in a thickness direction of the substrate toward thesubstrate, wherein the movable member is configured to be displacedtoward the substrate in a range in which recovery force of the beam islarger than electrostatic force which is formed between the substrateand the movable member, and when a position at which the electrostaticforce and the recovery force are equal to each other is a movablecritical point, the movable member is configured to contact thesubstrate prior to exceeding the movable critical point in a crosssectional view.
 2. The oscillator according to claim 1, wherein asurface of the substrate faces the movable member, and wherein themovable critical point is positioned at an opposite side of the surfaceof the substrate with respect to the movable member so that the movablecritical point is closer to the surface of the substrate than themovable member.
 3. The oscillator according to claim 2, wherein anelectrode is disposed on the substrate so that the electrode faces themovable member.
 4. The oscillator according to claim 2, wherein themovable member is configured to rotate about a rotary shaft along ain-plane direction of the substrate.
 5. The oscillator according toclaim 2, wherein concavities and convexities are formed at a location ofthe substrate where the movable member is configured to contact.
 6. Theoscillator according to claim 1, wherein an electrode is on thesubstrate so that the electrode faces the movable member.
 7. Theoscillator according to claim 6, wherein the member is configured torotate about a rotary shaft along an in-plane direction of thesubstrate.
 8. The oscillator according to claim 6, wherein concavitiesand convexities are formed at a location of the substrate where themovable member is configured to contact.
 9. The oscillator according toclaim 1, wherein the movable member is configured to rotate about arotary shaft along an in-plane direction of the substrate.
 10. Theoscillator according to claim 9, wherein the movable member has aprotrusion which outwardly protrudes from a tip end of the movablemember.
 11. The oscillator according to claim 10, wherein the substratehas a step which is provided at a position facing the tip end of themovable member, and the step has a portion that is concave toward anopposite side from the movable member.
 12. The oscillator according toclaim 10, wherein concavities and convexities are formed at a locationof the substrate where the movable member is configured to contact. 13.The oscillator according to claim 9, wherein the substrate has a stepwhich is provided at a position facing a tip end of the movable member,and the step has a portion that is concave toward an opposite side fromthe movable member.
 14. The oscillator according to claim 9, wherein anelectrode is disposed on the substrate so that the electrode faces themovable member.
 15. The oscillator according to claim 9, whereinconcavities and convexities are formed at a location of the substratewhere the movable member is configured to contact.
 16. The oscillatoraccording to claim 1, wherein concavities and convexities are formed ata location of the substrate where the movable member is configured tocontact.
 17. The oscillator according to claim 16, wherein the movablemember is configured to rotate about a rotary shaft along an in-planedirection of the substrate.
 18. An electronic device comprising: theoscillator according to claim 1; a display that displays an image; and ahousing that houses the oscillator and the display.
 19. A moving objectcomprising: the oscillator according to claim 1; and a movable body thathouses the oscillator.